Re: [XBoard-devel] Options and the manual

should we add a section in the manual with deprecated items or have
xboard output a warning/error when those items are used? I would prefer
that instead of just deleting them.

It depends on what you mean by 'deprecating'. I don't consider removing
undocumented options as deprecating anything. XBoard already gives an
error message on using non-existent options.
We did not deprecate any options recently. There seem to be some options
in the list for things that were deprected some 15 years ago, and I didn't
even propose to remove those. Just to not add their description to the manual.
As far as I am concerned the synonyms using hyphen for negation are not
very harmful either; I was just puzzled why we would have synonyms that
are not documented anywhere, with equally long names as the documented
versions.